Fireplace heat exchanger device



FIG. 1 is a perspective view of a fireplace heat exchanger device, showing our new design;

FIG. 2 is top plan view thereof;

FIG. 3 is front elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof; and

FIG. 6 is a rear elevational view thereof. 

The ornamental design for a fireplace heat exchanger device, as shown. 